Alysum,
I think you're on the right track to contact the dealer as it could be the bottom of the rudder tube perhaps wasn't bonded properly or sufficiently to the inside of the hull and Epic may help out with the repair. Epic rudders are fairly light weight and I and a couple of my mates have damaged more than a few of them very easily without any damage to the housing. An inspection of the inside of the hull may be the only way to confirm if the bond has failed. It's also the best way to get it fixed and you should do something about it sooner rather than later. It shouldn't be very expensive.
It's not an issue isolated to Epic by the way. Others report similar faults with other brands in the forum and varied responses from their dealers.
My ski, which is not an Epic, is leaking in this area and I recently fixed it by injecting resin with a syringe into the space around the tube from the outside. Perhaps "fixed" is too strong a word at the moment and I should say that I've temporarily made it watertight.
It's out of warranty BTW. After the "fix" I did did the old "Shake n Bake" trick. A little bit of detergent and freshwater into the breather hole, shake the ski around as much as you can to loosen the salt off the inside, empty the water out and leave it to bake in the sun with the breather hole open to get it dry inside.
Good luck with Epic and let us know how you get on with them.